2001GEKKO GTR MERC 350 MPI NOT STARTING

bananaron

Just got Gekko out of storage a wk ago and it was running fine.It was winterized last fall and had a new impeller ,oil filter change and tranny fluid replaced.This spring it seemed to run a little hotter usually at 170 instead of 150.Last night we made 2 long ski runs aand aftermy ski partner got in the boat turning the key all of the gauges and fuel pump reacted however nothing after turning the key.Yrs ago I replaced the neutral cut off swith and my first response was that however checking it both wires were on and moving the throttle linkage did nothing.We ha just replaced the bilge pump and were messing with the wires on the switch and so started to think perhaps my ski partner did something with the ignition switch.waited 15 minutes and it started.went out this morning and skied again however left it running when changing skiers and when back on the lift turned it off and tried to start it again and the same thing nothing .wiped the boat down and tried again and it started.could it be the neutral cut off switch or the ignition switch.it does seem to be running hotter temp however on this engine there is a audible horn when it reaches a higher temp.Any ideas would be helpful I hate to have to paddle home all the time....thx [

skihacker

Does it crank and not start or not crank over at all? I vaguely recall neutral switch will allow crank but cuts off fuel? Also think you're correct about overheating, would still run but you'd get the alarm screaming

bananaron

WHEN U TURN THE KEY THE GAUGES TURN ON AND THE FUEL PUMP MAKES A SOUND OTHERWISE NOTHING

MISkier

I don't know if this is still a thing, but I seem to recall starters getting hot could cause them to do nothing, as either the armature would swell or the solenoid would heat up and could not be overcome by the regular amperage of the battery. Later, when they cool/shrink, the battery power is enough to start it.

Skoot1123

If it is running hotter than you remember then I would check the raw water impeller. I know you put a new one in, but if it ingested something bad or got free of the bushing then it may not be pumping full flow through the engine.

Fastguy888

I had this issue on my 1995 Mercruiser 454 EFI SKI (MPI). Boat would run fine until it got hot and then either rough idle or dead ignition (probably from computer throwing a fault) until I let it cool down. It turned out to be a form of vapor lock through the VST (Vapor Separator Tank). This was somewhat a common issue, that I believe was also an issue on the 350's. Not sure if your year still used the same style VST tanks. Google "Mercruiser VST Start Issue" and their is a lot of info. In my case their was a diaphragm with a spring that was installed on the wrong side; their was a refresh on the diaphragm/spring orientation, but their was never a bulletin to the techs, so was common for them to install backwards.

Brokenstack

Sounds just like a bad starter solenoid to me. Symtoms I had on a mid 90s nautique were exactly the same.

6balls

Vapor lock it should still turn over but not start until cooling down. Bro Jim had that with the black scorpion in his gekko on hotter humid days

Rednucleus

Try giving the starter a gentle hammer tap next time it happens; if it goes time for a new starter

RRGR

Check your battery connections. I had something similar recently. Key on, all gauges worked, fuel pump did its thing, turned the key everything dead. Took me a bit, but tightened the connections and have been all set since.

Bookm_dano

+1 on battery connections... Particularly if gauges and fuel pump come on and then everything drops off when you try to engage starter.
Clean and tighten all the big wires. Positive and ground. In my case, it was the leads on the battery master switch.

LeonL

As @6ball said you can eliminate vapor lock if it won't crank. Most likely you can also eliminate battery connections since it cranks when cold, however it is a cost free action. I tend to agree with @MISkier that you have a starter problem. I would be concerned about the temp increase, but 20 degrees increase should not impact starting, unless your starter was hanging right on the border line of failure.

bananaron

Thanks for all of the ideas it seems to be okay at this time.Not sure what it was however we are still checking out different things.Still love this boat.....FANTASTIC WAKE AND PULL

Keith_Menard

This statement makes me believe it is a grounding issue/ battery issue.

I just added the zbox to my Gekko, it makes a good pull great.

thager

Check your battery clamps. Mine would not tighten down enough. Anytime it got humid I would get your symptoms. I replaced the clamps and problem disappeared.

BraceMaker

@thager when that happens a volt meter reading voltage between the post of the battery and the clamp will show voltage. If they are well connected there is no voltage difference between them.

So you go to the battery and you put the volt meter on the negative post and the negative clamp and have someone crank and under load the voltage that shows up is essentially the resistance between the clamp and the post.

Make sense? If for instance you made a bare ground wire 5' long and then you go to start the boat you'd expect zero volts to show up if you put both probes on the battery terminal, then to the clamp you'd expect a very small voltage, and then if you started going inch by inch down the wire you'd expect the voltage to go up because the resistance of that inch of wire is more than the resistance of no inches of wire so the "potential" between those two points goes up. (voltage drop). If you view this as voltage from one terminal to the other terminal negative to positive should read full battery voltage, and negative to negative should read zero volts. Over any leg of that wire the volt meter is reading how much the power would "prefer" to flow through your volt meter or rather how much it doesn't want to flow through the wire.

thager

@BraceMaker Thanks for the refresher! Never take a voltmeter with me when skiing. Would only happen occasionally, often weeks apart but always was humid. Would work fine. We shut the engine off anytime a skier is near the transom. Go to start and just dead. Nothing. Twist battery terminals by hand and starts right up. Finish skiing and go to dock then forget about it until it happens a few weeks later. Finally irritated enough to inspect clamps and found them too small for gauge wire used and the clamp alloy so stretched so it would not tighten sufficiently on post. That's my story and I'm sticking to it!

BraceMaker

@thager its all of those. You can find problems by physically twisting things or just by probing things and going A B C D.... till you find it. Personally a boat needs 3 tools, an set of high end pliers like a knipex, a 4 way screw driver, and a good multimeter like a fluke.

If you wanted to add to that kit, add some big hose clamps, electrical tape, maybe a few fuses and a length of mechanics wire (can be used as a fuse). And beyond that some spares like impellers and plugs.